Pump



May 27, 1930. P. A. s. I vERsEN 1,760,237

- PUMP Filed April e, 1927 6# /l s; y ,.,f g ,/14 1a N3 fwn/enfer.'

20a] rn/e, fcoz /er'few Patented May 27, 1930 UNITED STATES PATENT OFFICE I yPOTJI: ABNE SCOTT IVEBSEN, F GPENHAGEN, DENMARK PUMP Application tiled Aprl1.6,`1927, Serial No. 181,574, and in Denmark March 22, 1927.

The present invention relates to a -fuel pump which is intended -to deliver small quantities of a liquid under high pressure and which is particularly suited for internal vB combustion engines.

Such pumps work under particularly difiicult conditions as they must im art to the liquid uel'a very high pressure 300 atmospheres or much more) and must at the same time deliver very small quantities (only fractions o a cubic centimetre) at each stroke, and moreover these quantities must vary finely according to the momentary output of the engine. In order to meet these latter de- 15 mands all leakage of the pum must he avoided but it is very diiiicultto o tain this as the pump works under such very high pressure.

According to the present invention an absolute tightness is obtained by employing an auxiliary pump which acts initially to comress the uel on the outer side of the stuiiing ox and the inlet valve to the main pump or pump proper, to a pressure whichis only a little belowv the working pressure of the ump. This auxiliary pump, which is not intended to deliver the small quantities of fuel, need not be absolutely tight, but this is now easily Vobtained by the main pump, as the apparatus now works with a very small difference in pressure on the two sides of the stuffing chambers 2 and 3 for box andthe inlet valves.

In the accompanying drawing a sectional view, more or less diagrammatic, of one form of pumpin apparatus according to the invention is s own.

The pump consists of a body 1, in the interior of which are formed two cylindrical the auxiliary pump plunger 4 and the main or uel pump plunger 6, respectively. The plunger 4 reciprocates in the chamber 2, being driven in known manner from the shat of the engine and at the same time under control of the engine governor. The plunger 4 is packed by means of a stuiing box 5 of knownconstruction.

The main pump plunger 6 is built in one with rthis plunger 4, the arrangementbeing such that the two plungers 4 and 6 are disposed coaxially behind each other. The main -pump chamberl 3 is separatedfrom the auxilpump chamber 3,

iary pump chamber 2 by means of a stuliing box'? with a leather packing 8.

The auxiliary pump chamber is provided with an inlet valve 9 and a safety valve 10, which valves can be adjusted and are shown in the drawing as spring loaded balls. Behind the safety valve 10 there is bored in the pump body a passage 11 whichileads into an annular chamber 12 formed in the pump body and surrounding the plunger` 4. Another passage 13 connects the said chamber l2 with the inlet passage 14.. From the auxiliary pump chamber 2 an inlet passage 15 equipped with an adjustable inlet valve 16 leads to the main pump chamber- 3'; and from the latter chamber the outlet passage 17, controlled by the valve 18, leads to the injector or to the engine cylinder. v y

When the auxiliary plunger 4 mo -ves,out ward or downward, the suction thereby created in the auxiliary pum chamber 2 will open the inlet through passage 14 into said chamber, so that the pressure in the chamber duringthis period will be kept the same as that in the fuel tank or container (not shown) from which the fuel is supplied to passage 14, i. e., approximately atmospheric pressure. The annular chamber 12 is not uncovered by plunger 4 during its downward movement but, on the contrary, The main plunger 6, being attached to plunger 4, moves downward simultaneously with the same and thus creates whereby valve 16 will be caused to open and fuel will 'low from cham.'- ber 2 through passage 15 into chamber 3. Hence it will be apparent that at the end of the downward or suction stroke, both chambers 2 'and 3 will be illed with fuel.

The compression or upward stroke then commences, and during this stroke plunger 4 will compress the fuel in chamber 2 to an eX- tent determined by the adjustment of the safety valve 10, so that during the entire compression stroke a pressure is maintained in said chamberwhich, according to the invention, is only a trifie lower than the working pressure in the main pump chamber 3. en the pressure of the fuel becomes'great enough valve 9 and uel will be drawn v suction in the main too en valve 10, which takes place graduall l as t e plunger 4 continues its stroke, fuel W1 be forced out through said valve and then through passage 11 to the annular chamber 12, whence lit returns through passage 13 to the inlet passage 14.

The main plunger 6 moves upwardt of course, with the auxiliary plunger 4 durlng the compression stroke of the latter and, in consequence, creates the desired pressure 1n 4 chamber 3. This pressure, however, 1s some-l what higher than that determined in chamber 2 by the safety valve 10, so that the valve 16 will be kept closed; but valve 18, on the other hand, will be opened and the fuel compressed to high pressure in chamber 3 will be discharged therefrom through the dellvery passage 17 to the internal combustion engine.

v It will thus be seen that theauxiliary plunger 4 sucks in fuel at atmospheric pressure 'and itself produces the entire increase of pressure desired; whereas the main plunger 6 serves merely to keep the pressure on the outer side of packing 8 and valve 16, during the compression stroke of plunger 4, at nearly the same height as the worklng pressure of the latter, thus insuring complete tightness of these parts.

During the delivery perlod no oil Will be able to pass out through the stulling'box 7 8 or through the valve 16 from the mam pump chamber 3, because on the outer side of these parts there will be a pressure which is only a little lower than the working pressure and it will b`e easy to secure a perfect tightness 'for such small differences in pressure.

. The auxiliary pump plunger need not be builtin unit form with the main or fuel pump tain a similar pressure in a chamber corres onding to the auxiliary pump chamberv2 sliown here, so that the difference in pressure on the two sides of the stuffing box 7 and thev valve 16 will be small duringthe delivery period. l

What I claim as new is:

1. Pumping apparatus, comprising a main pump chamber and an auxiliary pump chamber, a reciprocating plunger in each chamber,

' stroke of the plungers, and will be discharged and a lsupply'passage leading from the auxiliary pump chamber to the main pumpichamber; both plungers making their corresponding strokes in unison, so that fluid will be drawn into the auxiliary pump chamber and supplied therefrom through said passage to the main pump chamber during the suction in small quantity under high pressure from said main pump chamber and simultaneously compressed in said auxiliary chamber to a pressure which is only slightly below the working pressure in the main pump chamberl during the compression stroke of the plungers.

2. Pumping apparatus, according to claim therefor; a stuiling box for through .the -stuiling v1 05 1, in which the two plungers are directly connected together to move as a unit in the same direction) 3'. Pumping apparatus, according to claim 1, in which an adjustable safety valve is associated with the auxiliary pump chamber to control the pressure therein.

4. Pumping apparatus, according to claim 1, in which an adjustable safety valve is' associated with the auxiliary pump chamber to vcontrol the pressure therein; and in which the two plungers are directly connected together to move as a unit in the same direction.

` 5.' Pumping apparatus, comprising a body formed with two alining chambers; an aux' iliary plunger Working in one chamber and a main plunger working inthe other chamber; an inlet valve for the auxiliary chember; a` supply passage leading from the latter chamberto the main chamber; and an outlet passage leading from said main chamber, both passages being equipped with normally closed valves; said plungers making their corresponding strokes in unison and in the same direction, so that fluid will be drawn into the auxiliary chamber and thence through thesupply passage into the main chamber so as to fill both chambers during the suction stroke of the plungers, and will be discharged in small quantity under high pressure from said main chamber through the outlet passage and simultaneously compressed in said auxiliary chamberto a pressure which is only slightly below the working pressure in the main chamber during the 100 compression stroke of the plungers.

'6. Single-stage pumping apparatus, comprising a main pump chamber; an .inlet valve said chamber; a

main plunger passing box and operating in said chamber for discharging small quantities of fluid under high pressure; an auxiliary pump chamber on the outerside of said st-uing box and said inlet valve; an auxiliary plunger for compressing the fluid in the auxiliary chamber to a pres-v sure only slightly below the working pressure in the main chamber; and an adjustable safety valve associated with the auxiliary chamber to control the pressure therein, said` auxiliary plunger making its pressure stroke during vthe pressure period of the lmain plunger so that the safety valve can open in safety during such period.

Single`-stage pumping apparatus, comprising a main pump chamber; an inlet valve therefor; a stulling box for said chamber; a

a pressure which is only slightly below the the fluid in the auxiliary chamber to a pressure which is only slightly below the working pressure in the main chamber; and an adjustable safety valve associated with the auxiliary chamber to control the pressure therein an inlet passage for the fluid and an overflow passage being provided, the overflow assage leading from the Safety valve to the inlet passage. .v

In testimony whereof I aix my signature. PO'UL ARNE SCOTT IVERSEN.

apparatus, comy ox for said chamber; a 

